Is it real or fake? How to check

Is it real or fake?
How to check If a diamond symbolizes commitment, promise and love, does that mean a faux diamond represents infidelity or dislike? What would you do if you purchased a piece of diamond jewelry, only to find out later you dropped thousands of dollars on a synthetic stone worth a fraction of that price?
No one wants to be deceived but, unfortunately, there are unscrupulous sellers out there who will sell you a fake diamond under the pretense of it being real. To protect yourself, there are a few ways you can test a stone before making a purchase to ensure you’re getting the “real deal.”
Buying a Diamond

Certification: Ask the jeweler for a certificate for the stone. Most independent jewelers or chain stores should be able to provide you with a diamond report or a certificate from a highly regarded laboratory like the Gemological Institute of America (GIA), which will prove the authenticity of the stone. Make sure you receive a certificate from a laboratory and not a simple “certificate of authenticity” created by the jewelry store itself. Shifty jewelers may create a certificate with fabricated grades for diamonds to make it look like you get a better stone than what you actually receive.
Laser Inscription: Find out if the diamond is laser inscribed with an ID number or other identifying mark. An inscribed ID number corresponds to a stone’s certification, ensuring its authenticity. These marks are inscribed on the diamond at the lab where it is graded; making sure the diamond will always be linked to its own paperwork.
These are two excellent methods to ensure you purchase a new, authentic diamond; but, what if you want to test the diamond in your great-grandmother’s heirloom necklace? Here’s the good news: Reiner’s Fine Jewelry in Houston has a whole bunch of tests to check for you.
The electric test: Diamonds are tremendous electrical conductors, which is one of the things that make them so useful for industrial purposes. At Reiner’s Fine Jewelry in Houston, we have a simple device for testing conductivity. A metal needlepoint touches to the stone – if a light goes off, voila, you have a real diamond on your hand. If the light doesn’t go off, it’s a safe bet you’re rocking a cubic zirconia (CZ).
The rainbow test: That prismatic effect diamonds get is called a rainbow. [Moissanite and cubic zirconia, the two most common diamond simulants] actually throw more rainbows and more fiery stuff than a diamond will. Both are slightly more refractive than diamonds, hence that extra fire.
The magnifying test: If you look at the edges of a real diamond, they’re always super pointed and crispy. Under high magnification, CZ and other simulates will show abrasions or scratches.
The weight test: CZ’s are much heavier than diamonds. This gets difficult to measure when the stone is in a ring setting, of course, but we can identify those weight discrepancies.
The flawless test: A final giveaway is that fakes look a little too perfect. If your rock has no visible inclusions (spots or flaws), you’ve probably got a fake. Either that, or you have a flawless diamond on your hands—in which case, congratulations, you can start planning your retirement.
For the most part, there’s really not much to worry about when it comes to shopping for diamonds; there’s very little chance that you’ll end up with a fake. No one’s going to be in business for longer than like 20 seconds if they’re selling fakes. So, just stay away from anyone selling an engagement ring out of the trunk of his or her car, and you should be fine.